在Roslyn分析器中查找字段和类型的有效可访问性

using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.CSharp;
using Microsoft.CodeAnalysis.CSharp.Syntax;
using Microsoft.CodeAnalysis.Diagnostics;
using System.Collections.Immutable;

[DiagnosticAnalyzer(LanguageNames.CSharp)]
public class FieldAccessibilityAnalyzer : DiagnosticAnalyzer
{
    public const string DiagnosticId = "FieldAccessibility001";
    private static readonly LocalizableString Title = new LocalizableResourceString(nameof(Resources.AnalyzerTitle), Resources.ResourceManager, typeof(FieldAccessibilityAnalyzer));
    private static readonly LocalizableString MessageFormat = new LocalizableResourceString(nameof(Resources.AnalyzerMessageFormat), Resources.ResourceManager, typeof(FieldAccessibilityAnalyzer));
    private static readonly LocalizableString Description = new LocalizableResourceString(nameof(Resources.AnalyzerDescription), Resources.ResourceManager, typeof(FieldAccessibilityAnalyzer));
    private const string Category = "Accessibility";

    private static readonly DiagnosticDescriptor Rule = new DiagnosticDescriptor(DiagnosticId, Title, MessageFormat, Category, DiagnosticSeverity.Warning, isEnabledByDefault: true, description: Description);

    public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics => ImmutableArray.Create(Rule);

    public override void Initialize(AnalysisContext context)
    {
        context.ConfigureGeneratedCodeAnalysis(GeneratedCodeAnalysisFlags.None);
        context.EnableConcurrentExecution();

        context.RegisterSyntaxNodeAction(AnalyzeFieldDeclaration, SyntaxKind.FieldDeclaration);
    }

    private static void AnalyzeFieldDeclaration(SyntaxNodeAnalysisContext context)
    {
        var fieldDeclaration = (FieldDeclarationSyntax)context.Node;
        foreach (var variable in fieldDeclaration.Declaration.Variables)
        {
            var symbol = context.SemanticModel.GetDeclaredSymbol(variable);
            if (symbol != null && symbol.DeclaredAccessibility == Accessibility.Public)
            {
                var diagnostic = Diagnostic.Create(Rule, variable.GetLocation(), symbol.Name);
                context.ReportDiagnostic(diagnostic);
            }
        }
    }
}